The present invention generally relates to electrical connectors and is more particularly directed to a tooless electrical connector that requires a low force to connect and a higher force to disconnect.
A variety of electrical devices utilize quick connect/disconnect connectors for conducting current from an electrical source to a lead. In general, such connectors include a housing, a spring and a lead with the current source provided by the housing. The current path is through the spring and into the lead. In order to insure positive connection, a set screw is typically used to lock the lead into the housing. This is necessary in order to provide the uniform conductivity between the lead and the housing.
While the set screw devices are functionable, they present a number of disadvantages. Specifically, due to the small size of miniconnectors, it is difficult to tighten the correspondingly very small screw. In addition, there is no structure, which provides a means for preventing over and under torquing of the set screw, which may result in an insecure coupling between the lead and the housing.
Further, if the set screw firmly holds the lead to the housing, there is no allowance for expansion, which may be caused by heating due to the conduction of electrical power, which may result in fatiguing of the lead.
Present invention provides for a tooless connection, that is, no set screw, in which the lead is positively retained in a position for insuring uniform electrical conductivity between the lead and the housing.
In one embodiment of the tooless electrical connector in accordance with the present invention a housing is provided which includes a bore with a groove disposed on an inside surface of the bore. The bore establishes a shoulder between a groove bottom and a bore inside surface.
A flat spring is disposed in the groove for defining a spring cavity between the flat spring and the shoulder and a circular canted coil spring is disposed within the spring cavity.
A pin having a tapered end and a body diameter sized for sliding engagement with the bore inside surface is provided and includes a circumferential groove in the pin body for receiving the coil spring upon insertion of the pin into the bore.
The flat spring includes a plurality of primary radial fingers formed therein which provides a means for retaining the coil spring in the cavity before insertion of the pin.
In addition, the flat spring includes a plurality of secondary radial fingers formed therein which provides a means for preventing axial movement between the housing and the pin with the coil spring within the pin groove. Preferably, the secondary fingers are shorter than the primary fingers. In addition, the primary and secondary spring fingers are preferably spaced apart from one another and extend inwardly from a common circumference.
In order to provide a large differential between connect and disconnect forces, the housing shoulder for compressing the coil spring along a minor axis thereof during disconnect of the pin from the housing bore is disposed at an angle to a normal to a conductor centerline between 5xc2x0 and about 45xc2x0, preferably, about 7xc2x0.
Control of the disconnect forces is also provided by a forward shoulder of the pin grove which is disposed at an angle of between about 1xc2x0 and about 90xc2x0 from the conductor centerline, preferably about 90xc2x0.
A number of coil springs may be utilized in the present invention, including radial coil springs and axial coil springs.
The coil spring may be initially disposed in the cavity with a major axis disposed within an included angle of between about 30xc2x0 and about 165xc2x0.
In one embodiment of the present invention, the coil spring is initially disposed in the cavity in a convex orientation and in another embodiment, the coil spring is initially disposed in the cavity in a concave orientation.
In yet another embodiment of the present invention, the flat spring comprises two spring elements, namely a first spring element comprising a plurality of primary radial fingers for retaining the coil spring in the cavity before insertion of the pin and the bore and a second spring element comprising a plurality of secondary radial fingers for preventing radial movement between the housing and the pin with the coil spring within the pin coil. In this embodiment, the primary radial fingers preferably are disposed adjacent to one another and the secondary radial fingers are in a spaced apart relationship with one another.